Dietary indices underpinning front-of-pack nutrition labels and health outcomes: a systematic review and meta-analysis of prospective cohort studies

Nutrient profiling systems are increasingly used to characterize the healthfulness of foods for front-of-package (FOP) labelling, which have been proposed as an effective public health strategy to help people make healthier food choices. To review available evidence from cohort studies that evaluated the association of dietary indices underpinning FOP nutrition labels with all-cause mortality, and incidence of cardiovascular diseases (CVD) or cancer. PubMed, Web of Science, and Scopus were systematically searched up to October 2023. We included articles if they were prospective cohort studies, if the exposure was any dietary index underpinning FOP nutrition labels (e.g., the modified Food Standard Agency-Nutrient Profiling System (FSAm-NPS), the Health Star Rating System, and others), and if outcomes were all-cause mortality or incidence of, or mortality from CVD and cancer. Random effects models were used to calculate the pooled hazard ratios (HRs) and 95% confidence intervals (CIs). We identified 11 records (7 unique prospective studies) that were included in the systematic review. The meta-analysis comprised eight studies analysing the FSAm-NPS dietary index (DI) as exposure. The pooled HRs associated with a 2-unit increase in the FSAm-NPS DI of all-cause mortality, CVD, and cancer risk were 1.06 (95%CI 0.99-1.13; I2=80%), 1.08 (95%CI 1.00-1.18; I2=70%), and 1.09 (95%CI 1.00-1.19; I2=77%), respectively. The Chilean Warning Label Score and the Health Star Rating systems were examined by one study each, and were significantly associated with the outcomes. Dietary indices underpinning most common FOP nutrition labels and reflecting nutrient-poor diets showed a tendency towards an increased incidence of CVD and cancer, but the observed effects were quite modest in magnitude. Further studies at the population level are needed to support the widely shared hypothesis that FOP labels, possibly in conjunction with other interventions, may contribute to reduce non-communicable disease risk.